This application is related to U.S. patent application Ser. No. 09/814,274 entitled xe2x80x9cFlextensional Transducer Assembly Including Array of Flextensional Transducersxe2x80x9d filed on even date herewith, assigned to the assignee of the present invention, and incorporated herein by reference.
The present invention relates generally to fluid drop ejectors, and more particularly to a flextensional transducer for ejecting droplets of a flowable material.
Fluid drop ejectors have been developed for ejecting droplets of a flowable material in a controlled manner. An example of a fluid drop ejector includes a flextensional transducer. As illustrated in FIGS. 1A and 1B, a conventional flextensional transducer 90 includes a cylindrical body 92, a circular flexible membrane 94 having an orifice 96 defined therein, and an annular actuator 98. The cylindrical body defines a reservoir for holding a supply of flowable material and the circular flexible membrane has a circumferential edge clamped to the cylindrical body. The annular actuator includes a piezoelectric material which deforms when an electrical voltage is applied. As such, when the piezoelectric material deforms, the circular flexible membrane deflects causing a quantity of flowable material to be ejected through the orifice from the reservoir.
One application of a flextensional transducer is in an inkjet printing system. As such, the inkjet printing system includes a printhead including a plurality of flextensional transducers which eject droplets of ink through orifices or nozzles to form an image on a print medium. One way to improve a quality of the image is to increase the resolution of the image. Resolution of the image is measured in dots-per-inch. To increase the resolution, therefore, the number of dots per inch must increase. Accordingly, the number of drops per inch must increase.
One way to increase the number of drops per inch is to increase the number of orifices or nozzles per unit of area of the printhead. Thus, a density of the flextensional transducers which eject the drops must increase. Therefore, for a fixed drop size, a spacing between the flextensional transducers and, more specifically, a spacing between the orifices or nozzles must decrease. Since the conventional flextensional transducer is cylindrical in shape, an arrangement of and/or spacing between the flextensional transducers is restricted by the cylindrical shape. Thus, increasing the density of a plurality of conventional flextensional transducers is limited.
Accordingly, a need exists for a flextensional transducer which provides greater flexibility in a design of an individual flextensional transducer as well as an arrangement of a plurality of flextensional transducers. More particularly, a need exists for a flextensional transducer which enables a compact array and, therefore, a greater density of orifices of a plurality of flextensional transducers.
One aspect of the present invention provides a flextensional transducer. The flextensional transducer includes a substrate having a fluid cavity defined therein, a flexible membrane portion supported by the substrate, and an actuator associated with the flexible membrane portion. The flexible membrane portion has a pair of spaced edges and an orifice defined therein which communicates with the fluid cavity. As such, the actuator is adapted to deflect the flexible membrane portion in response to an electrical signal.
In one embodiment, the fluid cavity is adapted to hold a supply of fluid therein such that the fluid communicates with the orifice of the flexible membrane portion. In one embodiment, the orifice of the flexible membrane portion defines a nozzle adapted to eject a quantity of the fluid in response to deflection of the flexible membrane portion.
In one embodiment, the pair of spaced edges of the flexible membrane portion are substantially linear. In one embodiment, the pair of spaced edges of the flexible membrane portion are curved.
In one embodiment, the fluid cavity has opposing sides and the pair of spaced edges of the flexible membrane portion follow the opposing sides of the fluid cavity. In one embodiment, the substrate includes opposing sidewalls which define opposing sides of the fluid cavity. In one embodiment, the sidewalls of the substrate are substantially linear. In one embodiment, the sidewalls of the substrate are curved. In one embodiment, the pair of spaced edges of the flexible membrane portion are positioned within the sidewalls of the substrate.
In one embodiment, the pair of spaced edges of the flexible membrane portion are formed by a pair of spaced slits in the flexible membrane portion. In one embodiment, the pair of spaced slits include spaced cuts through the flexible membrane portion. In one embodiment, the pair of spaced slits include spaced channels in the flexible membrane portion.
In one embodiment, the flexible membrane portion has an edge extending between the pair of spaced edges thereof. In one embodiment, the edge of the flexible membrane portion is oriented substantially perpendicular to the pair of spaced edges thereof. In one embodiment, the edge of the flexible membrane portion is formed by a slit in the flexible membrane portion.
In one embodiment, the flexible membrane portion is cantilevered over the fluid cavity. In one embodiment, the flexible membrane portion has a plurality of orifices defined therein.
In one embodiment, the actuator is provided on a side of the flexible membrane portion and positioned between the orifice and a supported end of the flexible membrane portion. In one embodiment, the actuator includes a first actuator and a second actuator such that the orifice is located between the first actuator and the second actuator. In one embodiment, the actuator includes a piezoelectric material.
Another aspect of the present invention provides a method of forming a flextensional transducer. The method includes defining a fluid cavity in a substrate, supporting a flexible membrane portion by the substrate, defining a pair of spaced edges of the flexible membrane portion, communicating an orifice of the flexible membrane portion with the fluid cavity, and associating an actuator with the flexible membrane portion. As such, the actuator is adapted to deflect the flexible membrane portion in response to an electrical signal.
Another aspect of the present invention provides a method of ejecting droplets of a fluid. The method includes supplying a fluid cavity with the fluid, extending a flexible membrane portion having a pair of spaced edges and an orifice defined therein over the fluid cavity such that the orifice communicates with the fluid cavity, and deflecting the flexible membrane portion relative to the fluid cavity to eject a quantity of the fluid through the orifice of the flexible membrane portion when the flexible membrane portion deflects.
Another aspect of the present invention provides a flextensional transducer. The flextensional transducer includes a substrate having a fluid cavity defined therein, a flexible membrane portion supported by the substrate and having an orifice defined therein which communicates with the fluid cavity, an actuator associated with the flexible membrane portion, and a compliant feature adjacent the actuator. The actuator is adapted to deflect the flexible membrane portion in response to an electrical signal. As such, the compliant feature facilitates deflection of the flexible membrane portion.
The present invention provides a flextensional transducer adapted to eject droplets of a fluid in a controlled manner. The flextensional transducer includes an actuator which deflects a flexible membrane portion in response to an electrical signal. The flexible membrane portion has spaced edges and an orifice defined therein such that deflection of the flexible membrane portion causes ejection of fluid from a fluid cavity and through the orifice. In addition, the present invention provides a flextensional transducer assembly which includes a plurality of flextensional transducers arranged in an array.